Duct



C. F. lLUMM 4DUCT Filed April 28, 1943 glu/verdor Patented Jan. 4, 1944y 6 Claims.

This invention 'r'elatesto ducts'fonafirmcon'db tioning systems, or thelikejandlias' Vfor its fprimary object to provide a duct vi'zhiclfi canbe made with. a minimum of metal, `but which will possess all of thedesirable qualities o 'f the`allf metal duct which it is to replace. V

Another object of the invention is to provide a simple and eicientfastening and assembling means for the duct parts. y f- Other objects ofthe invention `will become ap-b parent as the description proceeds,reference being had to the accompanying drawing, in which- Figure 1 is aperspective'view of a duct section constructed in accordance with thepresent invention; Fig. 2 is a top plan view thereof; Fig. 3 is afragmentary central vertical sectional View of a plurality of ductsections joined together; Fig. 4 is a section on line 4-4 of Fig. 3;Fig. 5 is a section on line 5--5 of Fig. 3, and Fig. 6 is a perspectiveview of a corner piece used in making up the duct sections, showing theassembling elements.

Referring to the drawing, the present invention contemplates theassembly of a duct for an air conditioning system, an exhaust system forgases, or the like, from a plurality of duct sections as is commonpractice, but instead of using metal for all of the duct walls,substitutes panels of non-metallic material held together by metalliccorner and end pieces. Alcompleted duct section is shown in Fig. 1 andcomprises panels I0, II, I2 and I3 of non-metallic material, thecharacter of the material depending on the service for which the duct isintended. For example, if very hot gases are to be passed through theduct, an asbestos board would be used, whereas plywood might be suitablefor a duct tobe used only for cool, dry air. i

The panels I0, II, I2 and I3 are held together by a metallic frame whichconsists of four corner pieces I4, and eight end pieces designated I6.Each of the corner pieces I4 consists of an angle section of appropriatelength carrying. panel-engaging clips I8 at spaced intervals along oneof its inner surfaces.l

The panel-engaging clips I8 are preferably formed from a single piece ofmetal and are stamped initially in the shape of an angle, one leg ofwhich is solid and the other leg of which is slotted to form individualfingers 20. l'Ihe solid leg of each clip is spot welded, or otherwisesuitably xed to the corner pieces in such a manner that the ngers 2D arespaced out from the corner piece by the thickness of the panel whichthey are intended to hold, as indicated in Fig. 5. A1-

ate nes fthe' nigerszo are iei intacte-sifin' whihthey a e formed whilethe Yrey inaind'r 'are ybent lozteltA int' pafallfelisinr with the solidportion of the clip to forni holding ngers 5 for another side panel, asshown in Figs. 5 and 6.

Assemblyf the'side panels after the clips'r are ben "isi therefore mer ya matter of inserting ich se""fngrs. I ,n

l connected ,together at v v d peesls which may be itli sptiwelddrrivted to the corner pieces, depending on7 the degree of rigiditydesired in the duct, a spot welded connection being more rigid than ariveted connection. Each of the end pieces carries panel-engaging clips22 which are bent over the ends of the panels to hold them againstlongitudinal displacement.

As is more or less common practice with allmetallic ducts, and as isshown inFigs. 1 and 3, vthe end pieces are dissimilar in that one set isprovided with an initially up-turned flange I6a to form a socket for thereception of end pieces kathy" of the other type, which ilange may becrimpedy over to lock the duct sections together. 25

sembled and the panels IIl, II, I2 and I3 inserted behind the clips I8,the lingers 20 of which are then bent to panel-engaging position. Theend clips 22 are then bent over the ends of the panels to preventlongitudinal displacement and the duct section is completed. `Inassembling a duct, it is only necessary to stack the sections one on topof the other if the duct is to be vertical and to crimp the upstandinganges I Iia in to hold the sections'together. `If the duct is to carrynoxious gases, it may be desirable to caulk the opening between the sidepanels, soas to make it air tight. 'I'his can be done after the duct isformed by the use of an ordinary caulking 40 gun.

I wish it understood that my invention is not limited to any specificconstruction,- arrangement or form of the parts, as it is capable ofnumerous modifications and changes without departing from the spirit ofthe claims.

Having thus described my invention, what I claim as new, and desire tosecure by United States Letters Patent, is:

1. In a duct of the class'described, a plurality of built-'up end to endsections each `comprising a metallic frame polygonal in cross-sectionhaving longitudinally extending corner .pieces angled in cross-sectionwith their angles facing inwardly and having cross pieces at each endconnecting the ends of the corner pieces at each side of In operation,the metallic frame may be as- 1 end have similar anges with edge lips toform, Y

sides for and to engage over the cross piece flanges of an adjoiningduct section.

3. A duct section of the class described, com-i prising longitudinallyextending corner pieces an- Q. guiar in cross-section, cross-piecesrigidly conv necting the corner pieces at each end to form a duct frameof polygonal form in cross-section and providing openings at each sideofthe frame, clips on some of said pieces and having angled fingers, anda panel at each side of the frame closing the opening therein andseating against said corner and cross pieces of the frame and held inposition by the angled ngers of said clips.

4. A duct section polygonal in cross-section comprising a frame havinglongitudinally extending corner pieces angular in cross-section withtheir open sides facing inwardly and their rflanges extending towardadjacent flanges of adjoining corner pieces at the same side of theframe, and cross pieces at each end of the frame lapping and connectingthe adjacent llanges of adjoining corner pieces, and a panel at eachside of the frame cooperating with the corner piece flanges and thecross pieces at a respective side to close such side and being disposedat the inner sides of said flanges and cross pieces, and means attachedto the frame to frictionally hold the panels in position therein.

5. An arrangement as called for in claim 4 wherein said cross pieces atboth ends of the duct section have outstanding flanges for the ilanges`of one section to seat on those of an adjoining section, and some ofsaid anges having lips at their edges for engaging over the seatingflanges to retain them in seated position.

6. A duct section of polygonal form in crosssection comprising ametallic frame having mined fingers of said clips.

CONRAD F. LUMM.

